NASA Astronomy Picture of the Day
August 22, 2025
A Tale of Two Nebulae
This colorful telescopic view towards the musical northern constellation Lyra reveals the faint outer halos and brighter central ring-shaped region of M57, popularly known as the Ring Nebula. To modern astronomers M57 is a well-known planetary nebula. With a central ring about one light-year across, M57 is definitely not a planet though, but the gaseous shroud of one of the Milky Way's dying sun-like stars. Roughly the same apparent size as M57, the fainter and more often overlooked barred spiral galaxy at the left is IC 1296. In fact, over 100 years ago IC 1296 would have been known as a spiral nebula. By chance the pair are in the same field of view, and while they appear to have similar sizes they are actually very far apart. At a distance of a mere 2,000 light-years M57 is well within our own Milky Way galaxy. Extragalactic IC 1296 (aka PGC62532) is more like 200,000,000 light-years distant. That's about 100,000 times farther away than M57 but since they appear roughly similar in size, former spiral nebula IC 1296 must also be about 100,000 times larger than planetary nebula M57. Look closely at the sharp 21st century astroimage to spot even more distant background galaxies scattered through the frame.
https://apod.nasa.gov/apod/astropix.html
Hurricane Erin Roils in the Atlantic
August 21, 2025
The first Atlantic hurricane in the 2025 season, Hurricane Erin rapidly intensified over the ocean as it approached the Caribbean and the U.S. Eastern Seaboard.
Although it did not make landfall, the powerful storm system sent heavy rain and strong winds to coastal areas of Puerto Rico, the Turks and Caicos Islands, the Bahamas, and the U.S. Atlantic coast.
This animation, composed of images acquired with the VIIRS (Visible Infrared Imaging Radiometer Suite) on the Suomi NPP satellite, shows Erin’s path from August 14 to 19.
The storm reached hurricane strength on August 15, then rapidly intensified from a Category 1 to a Category 5 storm in just over 24 hours.
Sustained wind speeds reached 160 miles (260 kilometers) per hour—the strongest associated with the storm—on August 16, when the hurricane was northeast of Puerto Rico.
Several environmental factors facilitated Erin’s rapid intensification, including light wind shear and a compact storm structure, according to a blog post by meteorologist Bob Henson.
Sea surface temperatures were also unusually warm for mid-August, and the storm’s swift movement over the ocean allowed it less time to churn up warm surface waters, helping sustain the heat as an energy source.
Erin was only the 43rd Atlantic hurricane to reach Category 5 since official records began in 1851 and the earliest in this location, noted University of Miami meteorologist Brian McNoldy.
Hurricane Erin continued on its westward path, weakening slightly after undergoing eyewall replacement cycles.
This common process for intense hurricanes decreases maximum wind speeds but expands the size of the wind field.
The eye of the storm was prominent on August 18, when the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor on NASA’s Terra satellite acquired the image above.
Outer bands of the storm lashed Caribbean islands as it passed nearby. Puerto Rico received heavy rains and high winds on August 17, according to news reports, and widespread power outages affected more than 147,000 customers.
The Turks and Caicos Islands and the Bahamas braced for tropical storm conditions, including dangerous surf, strong winds, and coastal flooding, through August 19.
Forecasts next showed Erin bending north to parallel the eastern coast of the United States as a Category 2 storm.
Despite staying hundreds of miles offshore, the hurricane was expected to whip up hazardous conditions all the way from Florida to Canada.
People in North Carolina’s Outer Banks were under an evacuation order, and the state’s governor declared a state of emergency. In New York and New Jersey, officials urged beachgoers to stay out of the ocean.
Forecasters warned of dangerous surf and rip currents, flooding, and beach erosion along the Eastern Seaboard.
https://www.earthobservatory.nasa.gov/images/154694/hurricane-erin-roils-in-the-atlantic
Hubble Observes Noteworthy Nearby Spiral Galaxy
Aug 22, 2025
This NASA/ESA Hubble Space Telescope image offers a new view of the nearby spiral galaxy NGC 2835, which lies 35 million light-years away in the constellation Hydra (the Water Snake).
The galaxy’s spiral arms are dotted with young blue stars sweeping around an oval-shaped center where older stars reside.
This image differs from previously released images from Hubble and the NASA/ESA/CSA James Webb Space Telescope because it incorporates new data from Hubble that captures a specific wavelength of red light called H-alpha.
The regions that are bright in H-alpha emission are visible along NGC 2835’s spiral arms, where dozens of bright pink nebulae appear like flowers in bloom.
Astronomers are interested in H-alpha light because it signals the presence of several different types of nebulae that arise during different stages of a star’s life.
Newborn, massive stars create nebulae called H II regions that are particularly brilliant sources of H-alpha light, while dying stars can leave behind supernova remnants or planetary nebulae that can also be identified by their H-alpha emission.
By using Hubble’s sensitive instruments to survey 19 nearby galaxies, researchers aim to identify more than 50,000 nebulae.
These observations will help to explain how stars affect their birth neighborhoods through intense starlight and winds.
https://science.nasa.gov/missions/hubble/hubble-observes-noteworthy-nearby-spiral-galaxy/
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